To provide cellular wireless communication service, a wireless service provider typically employs an access network that functions to connect one or more access terminals (e.g., cell phones, PDAs, laptops, netbooks, tablets, and/or other wirelessly-equipped devices) with one or more transport networks. In a typical access network, an area is divided geographically into a number of coverage areas, such as cells and sectors, each defined by a radio frequency (RF) radiation pattern from a respective base transceiver station (BTS). Within each coverage area, the BTS's RF radiation pattern may provide one or more wireless links, each on a carrier (or set of carriers), over which access terminals may communicate with the access network. In turn, the access network may provide connectivity with the public switched telephone network (PSTN), the Internet, and/or other transport networks.
The wireless links may carry communications between the access network and the access terminals according to any of a variety of wireless protocols. Depending on the protocol employed, each wireless link may also be divided into a plurality of channels for carrying communications between the access network and the access terminals. For example, each wireless link may include a plurality of forward-link channels, such as forward-traffic channels, for carrying communications from the access network to the access terminals. As another example, each wireless link may include a plurality of reverse-link channels, such as reverse-traffic channels, for carrying communications from the access terminals to the access network. Typically, the number of channels on a given wireless link, and thus the number of simultaneous communications the given wireless link can carry, is limited by hardware and/or protocol constraints. As such, an access network may try to conserve its limited supply of wireless link channels.
One common way an access network conserves channels is by employing a paging process to locate idle access terminals before assigning a traffic channel to those access terminals. For instance, when an access network receives a request to set up a communication with an idle access terminal operating in the access network, the access network may send a first page message for receipt by the idle access terminal in a first paging area, which may include one or more coverage areas (or portions thereof) that are near a reference location (e.g., the idle access terminal's last-known location). If the idle access terminal is located in the first paging area and responds to the first page message, the access network may then assign a traffic channel to the idle access terminal. Alternatively, if the idle access terminal is not located in the first paging area and/or does not respond to the first page message, the access network may send a second page message for receipt by the idle access terminal in a second paging area, which may include the first paging area and/or one or more other coverage areas (or portions thereof). The access network may continue this process until it locates the idle access terminal, pages the idle access terminal in all coverage areas, and/or reaches a time or attempt limit. This paging process may thus enable the access network to locate the idle access terminal before assigning a traffic channel to the idle access terminal.
For various reasons, a wireless carrier may employ multiple access networks in a geographic area, with each access network operating according to a different wireless protocol. For example, in a given geographic area, a wireless carrier may employ one access network operating according to EIA/TIA/IS-856 Rel. 0, Rev. A, or other versions thereof (hereafter “IS-856”) and another access network operating according to EIA/TIA/IS-2000 Rel. 0, Rel. A, or other versions thereof (hereafter “IS-2000”). In such a geographic area, a subscriber may then use a dual-mode or “hybrid” access terminal that is capable of receiving service from—and switching between—the different access networks. To enable this ability, a hybrid access terminal may be capable of performing scheduled “tuneaways” during which it temporarily tunes away from one access network and to the other access network, such that hybrid access terminal can receive page messages and other control-channel messages from the other access network. If the hybrid access terminal receives a page message during one such tuneaway, the hybrid access terminal may then remain tuned to that access network and begin an active communication with the access network.